Return mechanism for an automatically returning switch

ABSTRACT

Return mechanism for an automatically returning switch comprises a return spring of particular shape and means for mounting this return spring on the switch box. The return spring is made of a spring wire and includes a mounting portion in one plane and an arm, or bridging, portion in another plane, preferably normal thereto, for exerting a spring action on the switch actuator rod. The mounting means for the mounting portion of the spring includes at least one groove in the wall of the switch box which permits one arm portion to move independently of the other arm portion.

United States Patent Nakamura et a1.

[ 1 June 27, 1972 Makoto Yamamoto; Yukito Shintomi, all of Kawasaki,Japan [73] Assignee: Fujisoku Electric Co., Ltd., Kawasaki-shi,

Japan [22] Filed: June 1,1970

[21] Appl.No.: 42,022

[56] References Cited UNITED STATES PATENTS 3,345,488 10/1967 Siegal..200/153 K 3,333,067 7/1967 Du Rocher et al ..200/6 Primary ExaminerJ.V. Truhe Assistant Examiner-Gale R. Peterson Attorney-Pearson & Pearson[5 7] ABSTRACT Return mechanism for an automatically returning switchcomprises a return spring of particular shape and means for mountingthis return spring on the switch box. The return spring is made of aspring wire and includes a mounting portion in one plane and an arm, orbridging, portion in another plane, preferably normal thereto, forexerting a spring action on the switch actuator rod. The mounting meansfor the mounting portion of the spring includes at least one groove inthe wall of the switch box which permits one am portion to moveindependently of the other arm portion.

5 Claims, 9 Drawing Figures PATENTEDJUHZT 1972 3. 673 363 25 E 241 2| Q23 25 23 J an v 3' 25 22 22 FlG. 5a FlG.5b FlG.5c

INVENTOR T TADAHISA NAKAHURA HIROZI FUIIHO 0 3o 24 24 30 34b MAKOTOYAMANOTO-YUKITO SHINTOIH F l G. 6 BY Ewan-0'" PM ATTORNEY RETURNMECHANISM FOR AN AUTOMATICALLY RETURNING SWITCH BACKGROUND OF THEINVENTION l-leretofore there have been proposed various kinds of returnmechanism for an automatically returning switch. Among them, a returningmechanism of lapping plate type and a returning mechanism of coil springtype are the most typical examples, the former including a return plateof an M form mounted on a movable see-saw contact on which a followerslides, and the latter including coil springs arranged at opposite sidesof an actuator and utilizing the return force of the coil springs.

The former returning mechanism, however, has drawbacks in that (1) thedistance between the topmost points of the M shaped return plate and theceiling of the switch box cannot be greatly reduced as this would resultin deterioration of the electric insulation characteristic of the switchand (2) return plates having different form are required to obtainautomatic return action on one ON-position and two opposite ON positionof the switch having ON-OFF-ON characteristic.

The latter returning mechanism as mentioned above also has drawbacks inthat (1) the distance between the movable see-saw contact and theceiling of the switch box cannot be greatly reduced due to the verticalarrangement of the switch parts and (2) a greater number of parts arerequired and production, stocking etc. thereof becomes complex.

Thus, the returning mechanisms according to the prior art were notsatisfactory in the sense of reduction in height of the switch, andhence the minituarization thereof.

The principle object of this invention is to provide a returningmechanism for an automatically returning switch having none of thedefects of the conventional switch but having more superior technicalmerits.

SUMMARY OF THE INVENTION The returning mechanism according to thisinvention is characterized by a returning spring with particularconfiguration integrally made of a single spring wire, and by fixingmeans for fixing the returning spring onto a switch box.

The returning mechanism for a switch proposed in this inventioncomprises at least two terminals projecting from the switch box forconnection to outside circuits; a movable seesaw contact in electricalcontact with one of said terminals and having a fulcrum on said oneterminal and electrically making or breaking contact with the other ofsaid terminals; a rocking actuator rod having means secured at its tipfor driving said movable contact; at least one returning spring exertinga return action on said actuator rod; and groove means provided on theswitch box for fixing said returning spring thereto, said returningspring consisting of two mounting portions each having a curved portionat its bottom and two bridging portions connecting the upper ends ofsaid mounting portions to each other thereby oppositely spacing saidmounting portions, or consisting of a hook portion having a curvedportion at its bottom and an arm portion with one end turnedapproximately at a right angle with respect to the plane containing saidhook portion, and said returning spring being made of a single springwire, and said spring fixing means being a groove provided on theoutside surface of the wall of the switch box.

The return spring, which constitutes the main part of the returnmechanism of this invention, is made of a single spring wire and issimple in its configuration. This spring is also easy to produce andsuitable for mass production. Mounting of the spring on the switch isalso simplified by its particular configuration.

It is a more important merit of this invention that the minimum distancebetween the movable contact and the ceiling of the frame is not at alllimited by the switching mechanism. This is because, in assembly, thebridging portions or the arm portion of the return spring of thisinvention are positioned adjacent to or on the top of the box and themounting portions or the hook portion of the spring are mountedgenerally normal thereto in grooves on the side surfaces of the switchbox and therefore only the diameter of the spring wire has an efiect onheight of the switch. This permits the reduction in height of theswitch, and hence in the overall size thereof compared with the switchof prior art.

The above merits result in a decrease of production cost of the switch.

Viewing the return mechanism and in particular the return spring, ofthis invention from another aspect, it has also advantages in that thelife of the spring becomes longer in comparison with the conventionalone due to the fact that the tension is exerted all over the springduring operation.

In addition to the above, the applicability of the return spring isgreater than that of prior art in consideration of the fact that use ofa single return spring provides a switch which automatically returnsonly in one direction and use of two said return springs provides aswitch which automatically returns in two opposite directions.

The invention will be described in greater detail with reference to theaccompanying drawings in which:

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a perspective view of oneembodiment of a return spring of the present invention;

FIG. 2 is a perspective view of a switch box for use with the returnspring of FIG. 1;

FIG. 3 is a partially sectional plan view of the switch with the returnspring of FIG. 1 incorporated and with the top of the frame removed;

FIG. 4 is a partially sectional side view of the switch of FIG.

FIGS. 5a, 5b and 5c are a plan, a front and a perspective view,respectively of another embodiment of a return spring of the presentinvention;

FIG. 6 is a partially sectional plan view of the switch with the returnspring of FIGS. 5a, 5b and 5c incorporated and with the top of the frameremoved; and

FIG. 7 is a partially sectional side view of the switch of FIG. 6.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The return mechanism accordingto this invention comprises a return spring with an arm portion on oneplane, a mounting portion in another plane and groove means, in saidanother plane, provided on the switch box for mounting the return springon the box.

The return spring 1 is made of a single spring wire as shown in FIG. 1,and includes two mounting portions 2, 3 of U shape each having two legs2a, 2b; 3a, 3b and two bridging portions 4, 5 each bridging the upperends of the legs of said two mounting portions 2, 3, said two mountingportions 2 and 3 being oppositely spaced by said bridging portions 4 and5. The opposite ends of a single spring wire constituting the returnspring 1 form a closed loop and meet each other at the central lowerpoint of the mounting portion 3 as clearly shown in FIG. 1. The bridgingportions 4 and 5 extend in parallel to each other and in spacedrelationship so as to receive an actuator rod 12 (FIG. 4) therebetween.

The switch box 6 on which the return spring 1 is mounted and whichconstitutes a part of the return mechanism of this invention is shown inFIG. 2. This box 6 has two U shaped grooves 9, 10 on opposite side walls7, 8 for receiving legs 20, 2b and 3a, 3b of the mounting portions 2 and3 of the spring 1. The U shaped groove is of fixed width at its two legsand becomes narrower toward the central lowest point.

In assembly, the return spring 1 is positioned astride of the box 6 fromabove, and the legs 2a, 2b and 3a, 3b of the mounting portions 2 and 3are set into the grooves 9 and 10, respectively, thereby retaining thespring 1 rockingly. When mounted, the mounting portion is sustained atits central lowest point by the inside wall 10a of the groove andtherefore a gap is provided between the bridging portions 4, 5 and topsurface of the box 6 as seen from FIG. 4. The actuator rod 12 with adriving means 13 fixed at its tip for actuating the movable see-sawcontact 11 is put between the bridging portions 4 and 5 of the spring I.This rod 12 with a sleeve (not shown) put thereon .is secured to the topplate of the frame 14 rockingly. The frame plates 14a, 14b extendingdownward at opposite sides of the box 6 cover the legs 20, 2b and 3a, 3bof the spring I from outside of the box 6. The sleeve, driving means andmovable see-saw contact may be of any structure and thus no detailedexplanation thereof is made in the specification.

The operation of the switch with the above mentioned arrangement will bedescribed below:

In FIGS. 3 and 4, the actuator rod 12 is in its center position and thusthe circuits connected to the outside terminals 15, 16 and 17 are in offcondition.

In this condition, when the actuator rod 12 is moved in the direction Aby a force applied thereto, the rod 12 pushes the bridging portion 5 ofthe return spring 1 leftward and takes the position as represented by adotted line in FIG. 4. This results in that the movable see-saw contact11 is tilted by the driving means 13 to lower the left end thereof toits lowest position and to close the circuit connected to the terminalsand 16., In this operation, the leg 3a of the mounting portion 3 of thespring 1 opens outwardly relative to the central lowest point 30. Theactuator rod 12 continues to retain this condition so long as such aforce is applied. As shown, the legs 2b and 3b do not flex in thedirection A and remain seated against the walls of the islands of theirrespective grooves 9 and 10. Thus the force exerted on the actuator rod12 comes from deflection of the left half of the spring, substantiallyindependent of any force coming from the right half thereof, the righthalf remaining anchored in its half of the grooves. The force necessaryto drive the actuator rod 12 is therefore minimized and operation is bya relatively light touch. When the force exerted on the rod 12 isremoved, the rod 12 is caused to return to its center position by thespring restitution force stored in the bridging portion 5 and thecircuits connected to the terminals I5 and I6 are opened.

Similarly, when the actuator rod 12 is moved in the direction B by aforce applied thereto, the bridging portion 4 is moved rightward and thecircuit as connected to the terminals I6 and 17 is closed. With thisforce removed, the circuit is opened.

Explanation will be made on another embodiment of the return springaccording to this invention with reference to FIGS. 5a, 5b and 5c.

This return spring 21 is also made of a single spring wire, and includesa hook portion 22 and an arm portion 24, the latter being bentapproximately at a right angle at the end 23 of the straight portion ofsaid hook portion with respect to a plane containing said hook portion,and extending a desired distance from the plane.

In assembly, the return spring 1 is so mounted on the box 26 that thehook portion 22 of the spring 21 is set into a groove 29 provided on aside wall 27 of the box 26, and that the free end 25 of the hook portion22 abuts on the inside wall of the groove 29 and that the bent portion23 is positioned on the top edge of the box 26 and that the arm portion24 is positioned in contact with the actuator rod 32. Another returnspring is also mounted on the opposite side wall 28 of the box 26similarly. The shape of the grooves 29, 30 on the side walls 27, 28 ofthe box 26 need not necessarily be similar to that shown in FIG. 2.

When two return springs 21 are mounted on the same box 26, the armportions 24, 24 are juxtaposed and hold therebetween an actuator rod 32with a sleeve (not shown) thereon. This rod 32 is also secured to thetop plate of the frame 34 rockingly. The rod 32 has a driving means 33fixed at its tip for tilting the movable see-saw contact 31. The frameplates 34a and 34b of the frame 34 cover each hook portions 22 from theoutside thereof.

The operation of the switch with the return spring as mentioned abovewill be described in connection with FIGS. 6 and 7 In these drawings,the actuator rod 32 is in its center position and the circuits connectedto the outside terminals 35, 36 and 37 are in off condition.

In this condition, when the actuator rod 32 is moved in the direction A"against the arm portion 24 of the spring 21 by a force applied thereto,the rod 32 presses the arm portion 24 leftward, and thus the hookportion 22 expands with respect to the free end 25 thereof abutting onthe inner wall of the groove.

The rod 12 and the spring I take the position as shown in FIG. 7 by adotted line. The driving means 33 secured at the tip of the rod 32 tiltsthe movable see-saw contact 31 to its lowest position to close theoutside circuits connected to the terminals 35 and 36. When the forceapplied to the rod 32 is removed, the rod 32 returns to its centerposition by the restitution force stored in the arm portion 24 of thespring 1, and the circuit opens.

Similarly, when the actuator rod 32 is moved in the direction B by anapplied force, the driving means 33 tilts the movable contact 31 to itsopposite lowest position to close the outside circuits connected to theterminals 36 and 37. When the applied force is removed, the rod 32returns to its center position by the spring restitution force of thespring.

In the second embodiment as above mentioned, two similar return springsare used for the actuator rod to automatically return to its centerposition in two opposite directions. Ifa one way return is desired,however, a single return spring may be used. This is effective inincreasing the usages of the switch.

It is a matter of course that the return mechanism according to thisinvention is well applicable not only to a toggle switch but also to anyswitch.

It is to be understood that the embodiments described herein areillustrative only and are not intended as limiting the invention to theconstruction and arrangement of parts described.

We claim I. Automatically returning switch comprising:

at least two terminals projecting from a switch box for connection to anoutside circuit or circuits,

a see-saw contact in electrical contact with one of said terminals andadapted to rock within said box so as to make or break electricalcontact with the other terminal or terminals,

a rocking actuator with driving means secured at the tip thereof fordriving said see-saw contact,

two return springs exerting a spring action on said actuator,

and

means provided on said switch box for fixing said return springsthereto,

said returning springs each consisting of a hook portion having a curvedportion at its bottom and an arm portion with one end turnedapproximately at a right angle with respect to the plane containing saidhook portion,

said spring fixing means being a groove provided on the outside surfaceof the opposite walls of the switch box and having an island within saidgroove, and said island having a curvature at its lower part conformingto said curved portion of said hook portion of the spring said tworeturn springs being mounted within each of said grooves on said switchbox so that the arm portions of said springs can receive said actuatortherebetween.

2. An automatically returning switch comprising:

at least two terminals projecting from a switch box for connection to anoutside circuit, or circuits;

a see-saw contact in electrical contact with one of said terminals andadapted to rock within said box so as to make or break electricalcontact with the other terminal or terminals;

a rocking actuator with driving means secured at the top thereof fordriving said see-saw contact;

return spring means exerting a return action on said actuator, saidmeans including two arm portions, each on an opposite side of saidactuator, and each having a mounting portion extending substantiallynormal thereto; and

spring receiving means on said switch box for receiving said mountingportions, each said spring receiving means including a groove in theoutside surface of one of the walls of said switch box and an islandwithin said groove;

whereby said mounting portions have predetermined deflection movement insaid grooves.

3. An automatically returning switch comprising:

at least two terminals projecting from a switch box for connection to anoutside circuit, or circuits;

a see-saw contact in electrical contact with one of said terminals andadapted to rock within said box so as to make or break electricalcontact with the other terminal or terminals;

a rocking actuator with driving means secured at the top thereof fordriving said see-saw contact;

return spring means exerting a return action on said actuator, saidmeans including two arm portions, each on an opposite side of saidactuator, and each having a mounting portion extending substantiallynormal thereto;

spring receiving means on said switch box for receiving said mountingportions, each said spring receiving means including a groove in theoutside surface of one of the walls of said switch box and an islandwithin said groove; and

said return spring means comprising a spring wire with the said mountingportions thereof generally of U-shape and each said groove being ofU-shape with legs of predetermined width and a central, curved, lowerportion of reduced width;

whereby said mounting portions have predetermined deflection movement inthe legs of said grooves.

4. An automatically returning switch comprising:

at least two terminals projecting from a switch box for connection to anoutside circuit, or circuits;

a see-saw contact in electrical contact with one of said terminals andadapted to rock within said box to make or break electrical contact withthe other terminal or terminals;

a rocking actuator with driving means secured at the top thereof fordriving said see-saw contact;

return spring means exerting a return action on said actuator, saidmeans including two arm portions, each on an opposite side of saidactuator, and each having a mounting portion extending substantiallynormal thereto;

spring receiving means on said switch box for receiving said mountingportions, each said spring receiving means including a groove in theoutside surface of one of the walls of said switch box and an islandwithin said groove; and

said return spring means comprising a single spring wire forming asymmetrical closed loop;

whereby said mounting portions have predetermined deflection movement insaid grooves.

5. An automatically returning switch comprising:

at least two terminals projecting from a switch box for connection to anoutside circuit, or circuits;

a see-saw contact in electrical contact with one of said terminals andadapted to rock within said box to make or break electrical contact withthe other terminal or terminals;

a rocking actuator with driving means secured at the top thereof fordriving said see-saw contact;

return spring means exerting a return action on said actuator, saidmeans including two arm portions, each on an opposite side of saidactuator, and each having a mounting portion extending substantiallynormal thereto;

spring receiving means on said switch box for receiving said mountingportions, each said spring receiving means including a groove in theoutside surface of one of the walls of said switch box and an islandwithin saidgroove; and said return spring means comprises a pair ofIdentical springs each having a hook portion with a curve at its bottomforming said mounting portion and each having said am portion at its topwith one end turned approximately at a right angle with respect to theplane containing said hook portion, each said arm portion beingpositioned in contact with an opposite side of said actuator of theswitch, the said hook portion having a free end in engagement with theisland of the groove in which it is received;

whereby said mounting portions have predetermined deflection movement insaid grooves.

1. Automatically returning switch comprising: at least two terminalsprojecting from a switch box for connection to an outside circuit orcircuits, a see-saw contact in electrical contact with one of saidterminals and adapted to rock within said box so as to make or breakelectrical contact with the other terminal or terminals, a rockingactuator with driving means secured at the tip thereof for driving saidsee-saw contact, two return springs exerting a spring action on saidactuator, and means provided on said switch box for fixing said returnsprings theretO, said returning springs each consisting of a hookportion having a curved portion at its bottom and an arm portion withone end turned approximately at a right angle with respect to the planecontaining said hook portion, said spring fixing means being a grooveprovided on the outside surface of the opposite walls of the switch boxand having an island within said groove, and said island having acurvature at its lower part conforming to said curved portion of saidhook portion of the spring said two return springs being mounted withineach of said grooves on said switch box so that the arm portions of saidsprings can receive said actuator therebetween.
 2. An automaticallyreturning switch comprising: at least two terminals projecting from aswitch box for connection to an outside circuit, or circuits; a see-sawcontact in electrical contact with one of said terminals and adapted torock within said box so as to make or break electrical contact with theother terminal or terminals; a rocking actuator with driving meanssecured at the top thereof for driving said see-saw contact; returnspring means exerting a return action on said actuator, said meansincluding two arm portions, each on an opposite side of said actuator,and each having a mounting portion extending substantially normalthereto; and spring receiving means on said switch box for receivingsaid mounting portions, each said spring receiving means including agroove in the outside surface of one of the walls of said switch box andan island within said groove; whereby said mounting portions havepredetermined deflection movement in said grooves.
 3. An automaticallyreturning switch comprising: at least two terminals projecting from aswitch box for connection to an outside circuit, or circuits; a see-sawcontact in electrical contact with one of said terminals and adapted torock within said box so as to make or break electrical contact with theother terminal or terminals; a rocking actuator with driving meanssecured at the top thereof for driving said see-saw contact; returnspring means exerting a return action on said actuator, said meansincluding two arm portions, each on an opposite side of said actuator,and each having a mounting portion extending substantially normalthereto; spring receiving means on said switch box for receiving saidmounting portions, each said spring receiving means including a groovein the outside surface of one of the walls of said switch box and anisland within said groove; and said return spring means comprising aspring wire with the said mounting portions thereof generally of U-shapeand each said groove being of U-shape with legs of predetermined widthand a central, curved, lower portion of reduced width; whereby saidmounting portions have predetermined deflection movement in the legs ofsaid grooves.
 4. An automatically returning switch comprising: at leasttwo terminals projecting from a switch box for connection to an outsidecircuit, or circuits; a see-saw contact in electrical contact with oneof said terminals and adapted to rock within said box to make or breakelectrical contact with the other terminal or terminals; a rockingactuator with driving means secured at the top thereof for driving saidsee-saw contact; return spring means exerting a return action on saidactuator, said means including two arm portions, each on an oppositeside of said actuator, and each having a mounting portion extendingsubstantially normal thereto; spring receiving means on said switch boxfor receiving said mounting portions, each said spring receiving meansincluding a groove in the outside surface of one of the walls of saidswitch box and an island within said groove; and said return springmeans comprising a single spring wire forming a symmetrical closed loop;whereby said mounting portions have predetermined deflection movement insaid grooVes.
 5. An automatically returning switch comprising: at leasttwo terminals projecting from a switch box for connection to an outsidecircuit, or circuits; a see-saw contact in electrical contact with oneof said terminals and adapted to rock within said box to make or breakelectrical contact with the other terminal or terminals; a rockingactuator with driving means secured at the top thereof for driving saidsee-saw contact; return spring means exerting a return action on saidactuator, said means including two arm portions, each on an oppositeside of said actuator, and each having a mounting portion extendingsubstantially normal thereto; spring receiving means on said switch boxfor receiving said mounting portions, each said spring receiving meansincluding a groove in the outside surface of one of the walls of saidswitch box and an island within said groove; and said return springmeans comprises a pair of identical springs each having a hook portionwith a curve at its bottom forming said mounting portion and each havingsaid arm portion at its top with one end turned approximately at a rightangle with respect to the plane containing said hook portion, each saidarm portion being positioned in contact with an opposite side of saidactuator of the switch, the said hook portion having a free end inengagement with the island of the groove in which it is received;whereby said mounting portions have predetermined deflection movement insaid grooves.